The present invention relates to polymers having enhanced and durable hydrophilicity and rewetting properties, and a process of producing the same.
Many polymers such as aliphatic polyamides and polyesters are inherently hydrophobic. There is, however, a need for these polymers to be made durably hydrophilic and to have rewetting properties. There are various recognized methods for enhancing the hydrophilicity of polymers.
Hydrophilicity of polyamides (e.g., nylon) and polyester substrates has been achieved. For example, aliphatic polyamide and polyester polymers can be treated with appropriate hydrophilic add-on agents or coatings. The hydrophilic properties imparted to these substrates, however, are often not durable and are highly dependent on its laundering environment. The detergent employed for laundering may enhance or inhibit the hydrophilic and rewetting properties of the substrate.
It has generally been accepted that if polymers such as polyamides and polyesters can be made permanently hydrophilic it may possess rewetting properties. The converse is thought to be true as well; if a substrate can be made to rewet (i.e., absorb water), then it may be regarded as possessing hydrophilic characteristics.
An art-recognized alternative to add-on agents or coatings is the graft polymerization of the polymer with an appropriate hydrophilic copolymer. For example, U.S. Pat. No. 4,135,877 to Aikawa et al. proposes the graft polymerization of water-soluble vinyl monomers such as acrylic acid, acrylamide and N,N'-methylene-bisacrylamide onto polyamide fibers using heat and an aqueous treating solution containing acid. Hydrophobic vinyl monomers have been graft polymerized with nylon, polypropylene and polyesters, such as described, for example in U.S. Pat. Nos. 3,297,786 to Horowitz; 3,099,631 to Tanner; 3,252,880 to Magat et al.; and 3,097,185 to Armen. Often these techniques, however, result in diminished physical properties of the polymer substrate such as hand, fabric strength and thermal regulative properties.
Another alternative is the application of water-soluble polysiloxane-polyether copolymers into the anhydrous melt-spin phase of fiber production prior to extrusion, for example, as proposed in U.S. Pat. Nos. 5,132,392 to DeYoung et al. 4,761,455 to Chiba proposes improved surface appearance and sliding properties of extruded nylon resins. U.S. Pat. No. 4,460,962 to Ostrozynski et al. proposes silicone-sheathed polyester fibers.
It is therefore an object of the present invention to provide a polymer (e.g., aliphatic amide or polyester polymers) having enhanced hydrophilicity, rewetting, and thermal regulative properties, and a process for providing the same.